Junction box



Oct. 27, 1942. H. P. CHANDLER JUNCTION BOX Filed NOV. l2, 1941 Bg w v @d (Ittorneg Patented Oct. 27, 1942 UNITED STATES PATENT OFFICE JUNCTION BOX Application November 12, 1941, Serial No. 418,748

2 Claims.

This invention relates to explosion-proof electric cable glands and more particularly relates to cable-packing glands for junction boxes, switch housings, explosion-proof chambers and similar structures.

The object of this invention is to construct a packed cable inlet gland for a junction box or similar devices.

A further object of the invention is to construct a packed cable inlet gland for a switch, junction box or the like that will conne any possible explosion to the chamber wherein it occurs.

A still further object of the invention is to construct a packing gland for a cable that will resist the force of an explosion and prevent llames, etc. from igniting inflammable substances surrounding the housing in which said gland is mounted.

Other objects are to simplify the construction, decrease cost of manufacture, increase the safety factor and to greatly extend the useful life of the device in which the gland is employed.

Other and further objects will occur to those skilled in the arts to which this invention pertains as the description proceeds, which taken in connection with the accompanying drawing sets forth a preferred embodiment of the invention and selected modications thereof, but such disclosures are not to be constructed as a limitation of the invention which is limited only by the appended claims and any and all modifications, alterations and variations of structure coming within the spirit and scope thereof are deemed to be included herein.

In the drawing:

Fig. 1 shows an elevational view of one side of a junction box with parts broken away to show details of construction.

Fig. 2 is a side view thereof with parts in sectionto show details of construction.

Fig. 3 shows a vertical sectional view of a modied packing gland.

Fig. 4 shows a variation of the structure of Fig. 3.

Fig. 5 shows a modification of the cable clamp.

Power transmission cables in mines, powder mills, grist and grinding mills, etc. wherein there is great danger of explosion from sparks, arcs, etc. requires that all cable junctions, fuse clips, switches, etc., to and from which conductor cables are led, to be completely isolated from the atmosphere to thereby prevent sparks, arcs, etc. that might be drawn from aiecting the atmosphere external to the housing in which such devices are mounted and confining the explosion or combustion, if any, to the interior of such housing, enclosing the junctions, switches, etc. The hazards of a dust explosion or gas explosion, etc., are thereby sharply reduced since the ignition or detonating of inflammable or explosive mixtures from an electric spark or arc from such cable joints and switches is thereby materially reduced.

The embodiment of the above ideas is set forth in the accompanying drawing in which I indicates a housing supporting the terminals of cables 2 and 3 which terminate in appropriate connectors 5, 6, 'I and 8 secured to insulators 4, 4 by means of screws 9, 9 threaded into each insulator 4. Screws (only one of which is shown) I0, whose heads are seated in washers II of appropriate composition, hold the insulators 4, 4 in position in the housing I. A cover I2 is threadably secured in an appropriate aperture in the front of the housing for the purpose of gaining access to the interior of the housing. A bracket plate I3 appropriately apertured is associated with the back of the housing for the purpose of securing same to a xed support. A lock means I4 has been provided to prevent any unintentional turning of the cover I2. The cover I2 has projections I2a thereon to facilitate rotation thereof and the lock means I4 engages one of the projections I2a as shown.

Removably secured to the upper and lower ends of the housing by screws I6, I6, II, I1 is a differentially bored Coupling I5, appropriately flanged at I5a to receive said screws and threaded into appropriate bosses Ia integrally associated With the housing I. A lock means I8 is linked in and to the heads of each of the set screws at each end to prevent any but intentional removal from the device.

The coupling interiorly receives two composition bushings I9 and 20, the shoulder of one of which engages a ange collar in the coupling I5 and the latter is engaged by bell mouth ZI threaded into the coupling I5 and which is shouldered to engage a collar ange and one of the ends of bushing 2D to urge same inwardly. Disposed between the two bushings is a compressible packing 22 which upon compression by the bell mouth 2| firmly engages the cable 3 and prevents passage of gas, flame, etc. from the interior to the exterior. A lock means 23 is intended to prevent any but intentional rotation of the bell mouth 2|. The adjacent ends of the elements I9 and 20 are concaved, and the packing 22 disposed between these ends, to assist in compressing it and the bushings against cable 3.

adapted to receive a bell mouth 29 or a flexible protecting tube (not shown) when the cable is? loosely laid on the ground, etc. 1

The cup-shaped element 27 isfurther adapted to receive a counter-bored element 3B having ya collar or flange 3l thereon adapted to nt nush.

with the anged or bossed portion loof a junction box or other housing, and is intended to be welded to the flange or bossed portion, instead of bolted thereto as in Figs. 1 and 2.

The interior or" the element 33 isv bored tov receive a pair of compression elements 32 and 33 land also the counter-bored sleeve 3@ eachv of which seat cn the flange of element 36! and between the concaved ends of theelements 32 and S3 a quantity of compressible packing material is disposed. The function of the metal, sleeve 34 is merely to avoid the use of excessively thick sleeve elements 32 and 33, since the latter are preferably made of an insulating material. Upon rotating 2l and 3i) relatively of each other the gasket material 35 is compressed and by reason of the c-oncave ends acts to f rmlyygrip cable 26. The opening in the lower end of-ele ment 3B is made quite large andis adaptedto receive several sizes of cableranging in size from that shown in Fig. 3 to thatof Fig. 4.-. When the larger sizes 'of cable are employed,I the metallic sleeve S4 is eliminated; By the usevv of the construction dil, there need be no changing of that element when'diiTe-rent sized cables` are used, as all that need be altered or changed is the cup element 2l' and the' elements 32 and S3. Attention is invited to the fact that elements i9, Eil, 32, E3 are slightly compressible aiding further in making the joint` gas tight.

In the event the cable 2@ should move relatively of the packingl gland,' a strain relief or stop element 3l is provided about the cable which is adapted to abut against the gland and thereby take the tension oi of the insulators el, @or any other element to which the cables are connected.

The structure of Figs. 3 and 4 are extremely flexible, providing for various sizecables with a minimum of adjustment, and also providing for quickly and conveniently Aplacing cable 2'8 within a tube securable to thefreduced diameter end 28 of element 2l. It isalso contemplated that a grounding connection such as Zllmay be provided in these glands when desired,l it preferably becoming a part or" element Sil disposed interiorly of the housing to which it is secured;v

Fig. 5 shows a U bolt clamp Varrangeim'er'itto be placed about a portion of the bell mouth 2i of Fig. 1, in which the bell mouthy 33 4has a severed portion 353 extending partially about the bell mouth 3G and formed by making two partial circumferential and one axial saw-cut therein as shown and over which said U bolt 4i) is placed to firmly clamp and securely fasten the bell mouth 3s and liner lll to a cable passing therethrough. This clamp not only prevents slipping of the cable within the gland but acts to assist in the prevention of leakage as well.

From the foregoing it is apparent that an explosion-proof gland has been perfected which functions as a check valve in that it may allow a certain amount of gases, etc. to slowly enter' the housing, but will prevent sudden exiting of the. gases such as would be caused by explosions, etc. No part of the glands will permit passage of the explosive gases.

That which is regarded new, novel and useful and which is sought to be protected by Letters Patent of the United States is as follows.

What is claimed is:

1. In a cable packing gland; a cable within said gland; a first member securaole to a housing; a second member threaded to said first member; an internal flange on one of said members; a shouldered sleeve member within said members adapted to engage said flange, said sleeve having an internal flange; a fiber sleeve fitted over said cable, one end of which is adapted to abut the wall of one of said members; a second fiber sleeve over said cable, one end of which is shouldered to engage the internal ange of said shouldered sleeve; said shouldered sleeve member and said nber sleeves interchangeable with other diierently bored sleeves adapted to receive differently diametered cables; a packing element disposed between said sleeve elements; and said packing element adapted to snugly engage said cable wheny said members are relatively rotated.

2. In a gas-tightpacking gland for a junction box; a `first member securable to a housing; a second member cooperating therewith and threaded thereto; one of said members provided with an internal flange; a sleeve element dis` posed within said members having a shoulder engaging said flange, said sleeve having an internal flange; a cable passing through said members; a fiber sleeve 'snugly fitting said cable and engaging the end of one of lsaid members, the other end of said sleeve' being cupped; a second liber sleeve on said cable having one end shouldered to engage said flange with the other .end cupped and extending toward the cupped end of said other sleeve; said shouldered sleeve member and said be'r sleeves interchangeable with vother differently bored sleeves a'daptedto re- 

